Washing machine

ABSTRACT

A washing machine is provided. The washing machine includes: a washing tub having an axis extending longitudinally; a circulation path configured to draw detergent solution mixed with a detergent in the washing tub and return the detergent solution into the washing tub from an upper side; a pump configured to pump the detergent solution in the washing tub into the circulation path and allow the detergent solution to rise in the circulation path; and a controller configured to execute a washing operation. The washing operation includes a circulation-soaking process during which a circulation process and a soaking process are conducted alternately and repeatedly. The detergent solution is circulated between the washing tub and the circulation path by driving the pump and sprayed onto washings in the circulation process. The pump is stopped from being driven and, the washings are soaked with the detergent solution in the washing tub in the soaking process.

TECHNICAL FIELD

The present disclosure relates to a washing machine.

TECHNICAL FIELD

When washings are washed with detergent solution mixed with a detergentin a washing machine, the higher the concentration of the detergentsolution is, the greater the washing effect caused by the detergentsolution will be. In a drum-type washing machine disclosed in thefollowing patent document 1, detergent solution of high concentration isdistributed to the washings inside the drum from a hollow shaft of thewashing machine. In a drum-type washing machine disclosed in thefollowing patent document 2, washing water of high concentration issprayed onto the washings in the drum, so that the washings can undergoa highly concentrated washing.

Prior to a main washing process of washing the washings normally,sometimes washings need to be soaked. The washings are soaked in thedetergent solution during a soaking to make dirt dissolve out, causingit easier to remove the dirt in the subsequent main washing process.Generally, the soaking is performed by utilizing the detergent solutionthe amount of which is substantially the same as that during the wholemain washing process. In the case that the washing effect of soaking isimproved by increasing the concentration of the detergent solution, acost of the detergent increases if the amount of the detergent isincreased.

Conversely, if the concentration of the detergent solution is increasedby decreasing the amount of water without increasing the amount of thedetergent, it is difficult to spray the detergent solution to thewashings uniformly because only little detergent solution is produced.In particular, unlike the drum-type washing machine disclosed in PatentDocument 1 and the drum-type washing machine disclosed in PatentDocument 2, for a vertical type washing machine including a washing tubthe axis of which extends longitudinally, the detergent solution tendsto be stored at the bottom of the washing tub, thus there is apossibility that only lower part of the washings in the washing tub issoaked in the detergent solution. In this way, it is difficult toimprove the cleaning effect of the washings by the detergent solution.

RELATED TECHNICAL LITERATURES Patent Literatures

Patent Literature 1: Japanese Laid-Open Patent Publication No.2005-65873

Patent Literature 2: Japanese Patent Publication No. 2008-534049

SUMMARY The Problem to be Solved by the Present Disclosure

The present disclosure is made in view of the above, and aims to providea washing machine capable of improving the cleaning effect with littledetergent solution in a structure accommodated with washings in awashing tub having an axis that extends longitudinally.

The Solution to the Technical Problem

The present disclosure relates to a washing machine, including a washingtub having an axis extending longitudinally, where the washing tub isconfigured to accommodate washings and is capable of storing water; acirculation path configured to draw detergent solution mixed with adetergent in the washing tub and return the detergent solution into thewashing tub from an upper side; a pump configured to pump the detergentsolution in the washing tub into the circulation path and allow thedetergent solution to rise in the circulation path; and an executionunit configured to execute a washing operation. The washing operationincludes a circulation-soaking process during which a circulationprocess and a soaking process are conducted alternately and repeatedly.The detergent solution is circulated between the washing tub and thecirculation path by driving the pump and sprayed onto washings in thecirculation process. The pump is stopped from being driven and thewashings are soaked with the detergent solution in the washing tub inthe soaking process.

Furthermore, the washing machine according to the present disclosureincludes a motor for rotating the washing tub. The execution unit isconfigured to drive the motor to rotate the washing tub at a low speedbelow a predetermined rotation speed in at least one circulationprocess.

Furthermore, the washing machine according to the present disclosureincludes a motor for rotating the washing tub. The execution unit isconfigured to drive the motor to rotate the washing tub repeatedly anintermittently in at least one circulation process.

Furthermore, the washing machine according to the present disclosureincludes a motor for rotating the washing tub. During thecirculation-soaking process, the execution unit is configured to causethe washing tub to stop in the circulation process, and drive the motorto rotate the washing tub merely for a predetermined angle prior tostarting a next circulation process.

Furthermore, the washing machine according to the present disclosureincludes a water supply path configured to supply water to the washingtub, and a water supply valve configured to open and close the watersupply path. The washing operation includes a washing process consistingof the circulation-soaking process and a normal washing process. In thenormal washing process, water is accumulated in the washing tub toperform a normal washing of the washings after the circulation-soakingprocess. During the circulation-soaking process, the execution unit isconfigured to open the water supply valve, so as to supply a part of atotal water supply amount in the whole washing process to the washingtub and generate the detergent solution.

Furthermore, the washing machine according to the present disclosureincludes a detergent container connected to the water supply path andcontaining the detergent. The water supply path is provided with adischarge opening, and water flowing through the water supply path afterpassing through the detergent container is discharged from the dischargeopening toward a position away from the washings in the washing tub.

Furthermore, the execution unit is configured to change a time forperforming the circulation process and a time for performing the soakingprocess according to load amount of the washings inside the washing tub.

The Effect of the Present Disclosure

According to the present disclosure, a washing machine accommodateswashings and stores water in a washing tub having an axis extendinglongitudinally. Inside the washing tub, the detergent solution mixedwith a detergent is pumped into the circulation path by a pump, rises inthe circulation path, and then returns into the washing tub from theupper side.

The execution unit executes a washing operation including acirculation-soaking process, in which a circulation process and asoaking process are conducted alternately and repeatedly. The detergentsolution is circulated between the washing tub and the circulation pathby driving the pump and sprayed onto washings in the circulationprocess. The pump is stopped from being driven and the washings aresoaked with the detergent solution in the washing tub in the soakingprocess.

Even if there is little detergent solution, the detergent solution isrepeatedly sprayed onto the washings in the washing tub by a pluralityof circulation processes, and thus is uniformly sprayed to the washings.Through the soaking process after each circulation process, the sameeffect identical to steeping can be obtained. As a result, dirt iseffectively dissolved out of the whole washings. Therefore, the cleaningeffect can be improved with little detergent solution.

Further, according to the present disclosure, the execution unit isconfigured to drive the motor to rotate the washing tub at a low speedbelow a predetermined rotation speed in at least one circulationprocess. Thus, the detergent solution returned to the washing tub fromthe circulation path can be uniformly sprayed onto the washings in thewashing tub over the entire region in the rotation direction of thewashing tub. Therefore, it is possible to further improve the cleaningeffect brought by the detergent solution.

Further, according to the present disclosure, the execution unit isconfigured to drive the motor to rotate the washing tub repeatedly andintermittently in at least one circulation process. Thus, the detergentsolution returned to the washing tub from the circulation path can beuniformly sprayed onto the washings in the washing tub over the entireregion in the rotation direction of the washing tub. Therefore, it ispossible to further improve the cleaning effect brought by the detergentsolution.

Further, according to the present disclosure, in the circulation-soakingprocess, the execution unit is configured to stop the washing tub duringthe circulation process, and drive the motor to rotate the washing tubfor a predetermined angle before starting the next circulation process.As a result, when the washing tub is stopped in the circulation process,it is possible to spray the washing water intensively in one part of thewashing tub containing the washings in the rotation direction. Then, thewashing tub rotates a little before starting the next circulationprocess, so that in the next circulation process, the washing water issprayed intensively to the other parts except the part where the washingwater was sprayed in the previous circulation process of the washings.By repeating the circulation process several times while graduallychanging the position where the detergent solution is sprayed to thewashings in such a manner, a sufficient amount of detergent solution iseventually sprayed to the washings in the washing tub from the region ofthe washing tub in the rotation direction. Therefore, it is possible tofurther improve the cleaning effect brought by the detergent solution.

Further, according to the present disclosure, in the case that thewashing process is constituted by the circulation-soaking process and anormal washing process, the execution unit is configured to open thewater supply valve in the circulation-soaking process before the normalwashing process to supply water to the water supply path, so that a partof a total water supply amount determined throughout the washing processis supplied to the washing tub to generate the detergent solution. As aresult, a detergent solution of high concentration can be produced.

Further, according to the present disclosure, the discharge opening ofthe water supply path discharges the water containing the detergentpassing through the detergent container toward the position away fromthe washings in the washing tub. As a result, it is possible to preventthe following situation: the detergent having an excessively highconcentration only adheres to a part of the surface of the washings Qbefore being dissolved into the water, so that it is difficult to cleanthe entire washings uniformly.

Further, according to the present disclosure, since the execution unitis configured to change the time for performing the circulation processand the time for performing the soaking process according to the loadamount of the washings in the washing tub, the most suitablecirculation-soaking process is performed according to the load.Therefore, the cleaning effect brought by the detergent solution in thecirculation-soaking process can be further improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating a washing machine according toan embodiment of the present disclosure.

FIG. 2 is a block diagram illustrating an electrical structure of thewashing machine.

FIG. 3 is a flowchart illustrating a control operation in acirculation-soaking process.

FIG. 4 is a schematic view illustrating a washing machine according to afirst modification.

FIG. 5 is a schematic diagram illustrating a washing machine accordingto a second modification.

FIG. 6 is a schematic view illustrating a washing machine according to athird modification.

LIST OF NUMERALS

1: Washing machine; 4, Washing tub; 5, Motor; 6, Water supply path; 6B:Discharge opening; 7: Water supply valve; 8, Detergent container; 11,Circulation path; 12, Pump; 30, Controller; J: Axis; Q, Washings; Z1:Upper side

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the drawings. FIG. 1 is a schematic diagramillustrating a washing machine 1 according to an embodiment of thepresent disclosure. An up-down direction in FIG. 1 is called as anup-down direction Z of the washing machine 1, and a left-right directionin FIG. 1 is called as a lateral direction Y of the washing machine 1.The up-down direction Z coincides with the vertical direction, and thelateral direction Y coincides with the horizontal direction. In theup-down direction Z, the upper side is referred to as an upper side Z1and the lower side is referred to as a lower side Z2. Although thewashing machine 1 may be a washing/drying machine having a dryingfunction, the washing machine 1 will be described by taking a washingmachine, in which the drying function is omitted and only the washingoperation is executed, as an example. The washing machine 1 includes ahousing 2, an outer tub 3 disposed in the housing 2, a washing tub 4, amotor 5, a water supply path 6, a water supply valve 7, a detergentcontainer 8, a drainage path 9, a drain valve 10, a circulation path 11and a pump 12.

The housing 2 is, for example, made of metal, and is formed in a boxshape. An entrance 2B for communicating the inside and outside of thehousing 2 is formed at an upper surface 2A of the housing 2. The uppersurface 2A is provided with a door 14 for opening/closing the entrance2B and a display operation portion 15 including a switch, a liquidcrystal panel and the like. A user operates the switch or the like ofthe display operation portion 15 to turn on/off the power of the washingmachine 1, set a washing operation mode freely, or issue an instructionfor activating or stopping the washing operation to the washing machine1. Information related to the washing operation is visually displayed onthe liquid crystal panel or the like of the display operation portion15.

The outer tub 3 is, for example, made of resin, formed into a bottomedcylindrical shape and elastically supported by the housing 2 via anelastic supporting member (not shown) such as a so-called hanger rod.The outer tub 3 can store water therein. An imaginary straight linepassing through a center of the circle of the outer tub 3 is axis J ofthe outer tub 3. The axis J extends in the vertical direction or in adirection slightly inclined with respect to the vertical direction, thatis, in a longitudinal direction. The bottomed cylindrical outer tub 3includes a substantially cylindrical circumferential wall 3A arrangedaround the axis J, a disk-shaped bottom wall 3B for sealing thecircumferential wall 3A from the lower side Z2, and a ring-shapedannular wall 3C formed by crimping an upper edge of the circumferentialwall 3A to protrude toward the axis J. The outer tub 3 is formed with acircular entrance 3D which is encircled by the annular wall 3C andopposed to the entrance 2B of the housing 2 from the lower side Z2, anda through hole 3E penetrating the center of the bottom wall 3B in thevertical direction Z.

The washing tub 4 is a metallic drum formed into a bottomed cylindricalshape slightly smaller than the outer tub 3, and can accommodate thewashings Q therein. The washing tub 4 is coaxially arranged in the outertub 3. Therefore, the axis of the washing tub 4 is the axis Jaforementioned. The bottomed cylindrical washing tub 4 includes asubstantially cylindrical circumferential wall 4A arranged around theaxis J, a disk-shaped bottom wall 4B for sealing the circumferentialwall 4A from the lower side Z2, a ring-shaped annular wall 4C formed bycrimping an upper edge of the circumferential wall 4A to protrude towardthe axis J. The washing tub 4 is formed with a circular entrance 4Dwhich is encircled by the annular wall 4C and opposed to the entrance 3Dof the outer tub 3 from the lower side Z2, and a plurality of throughholes 4E formed on the circumferential wall 4A or the bottom wall 4B.

When the door 14 described above is opened, the entrance 2B, theentrance 3D and the entrance 4D are aligned in the vertical direction Zand are exposed to the upper side Z1 from the upper surface 2A of thehousing 2, so that the washings Q are threw into/taken out of thewashing tub 4 by means of the entrances. The water in the outer tub 3flows between the outer tub 3 and the washing tub 4 via the throughholes 4E, and is stored in the washing tub 4. Therefore, the water levelin the outer tub 3 and the water level in the washing tub 4 coincidewith each other. At the circular center of the bottom wall 4B, arotation shaft 17 protruding to the lower side Z2 along the axis J isprovided. The rotation shaft 17 is inserted into the through hole 3E ofthe bottom wall 3B of the outer tub 3 from the upper side Z1.

The motor 5 is constituted by, for example, a frequency conversionmotor. The motor 5 is disposed on the lower side Z2 of the outer tub 3in the housing 2, and is fixed to the bottom wall 3B of the outer tub 3via a fixed part (not shown) or the like. The motor 5 has an outputshaft 18 that rotates about the axis J. The output shaft 18 is connectedto the rotation shaft 17 of the washing tub 4. When the motor 5 isdriven, the driving force generated by the motor 5 is transmitted fromthe output shaft 18 to the rotation shaft 17 to drive the washing tub 4to rotate around the axis J. It should be noted that a transmissionmechanism (not shown) consisted of a clutch or the like may also besandwiched between the rotation shaft 17 and the output shaft 18.Further, the washing tub 4 is provided with a pulsator (not shown) thatrotates to stir the contained washings Q, and the driving force of themotor 5 may be selectively transmitted from the transmission mechanismto one or both of the washing tub 4 and the pulsator. In addition, inthis embodiment, for convenience of explanation, the rotation number ofthe motor 5 is the same as the rotation number of the washing tub 4 andthe pulsator.

The water supply path 6 is a flow path which has one end 6A connected toa faucet (not shown) and the other end 6C formed with a dischargeopening 6B. The other end 6C of the water supply path 6 penetrates theannular wall 3C of the outer tub 3 from the upper side Z1, and thedischarge opening 6B is configured to face a gap 19 in the lateraldirection Y between the circumferential wall 3A of the outer tub 3 andthe circumferential wall 4A of the washing tub 4 from the upper side Z1.

The water supply valve 7 is provided in the water supply path 6. Whenthe water supply valve 7 is opened, the water supply path 6 is opened.In this way, through the water supply path 6, the water from the faucetflows down to the gap 19 from the discharge opening 6B, and isaccumulated in the outer tub 3, as shown by a thick solid arrow. At thistime, the discharge opening 6B discharges the water flowing through thewater supply path 6 toward the gap 19 between the outer tub 3 and thewashing tub 4, that is, the discharge opening 6B discharges the watertoward a position away from the washings Q in the washing tub 4. Thewater accumulated in the outer tub 3 passes through the through holes 4Eof the washing tub 4 to be accumulated in the washing tub 4. In thisway, when the water supply valve 7 is opened, the water is supplied tothe washing tub 4 from the water supply path 6. On the other hand, thewater supply path 6 is closed when the water supply valve 7 is closed,and thus no water is supplied.

The detergent container 8 is formed as a box for containing thedetergent, and is connected to the middle of the water supply path 6.The internal space of the detergent container 8 constitutes a middlesection of the water supply path 6. When the water supply valve 7 isopened to supply water, the water from the faucet passes through thedetergent container 8 to carry the detergent, flows through the watersupply path 6 and is supplied from the discharge opening 6B to the outertub 3 and the washing tub 4. As a result, the detergent solution mixedwith the detergent is stored in the outer tub 3 and the washing tub 4.

The drainage path 9 is a flow path having an end 9A and another end 9B.The end 9A is connected to the bottom wall 3B of the outer tub 3 fromthe lower side Z2 at a position other than the through hole 3E. The end9B is drawn out of the housing 2 at a position lower than the end 9A.

The drain valve 10 is provided in the drainage path 9. When the drainvalve 10 is opened, the drainage path 9 is opened. Accordingly, thedetergent solution accumulated in the outer tub 3 and the washing tub 4is discharged to the outside of the machine through the drainage path 9.In this way, after the water is drained off, the drainage path 9 isclosed when the drain valve 10 is closed, thus the drainage is stopped.

The circulation path 11 is a flow path having an end 11A and another end11C. The end 11A is connected to a section of the drainage path 9, whichis between the end 9A and the drain valve 10. The end 11C is formed witha discharge opening 11B. The circulation path 11 is bent after extendingin the lateral direction Y from the end 11A, extends to the upper sideZ1 through a gap between the housing 2 and the outer tub 3, and is benttoward the axis J side to reach the end 11C. The end 11C is bent towardthe lower side Z2 just above the entrance 3D of the outer tub 3. Thedischarge opening 11B opens at the lower end of the end 11C, and facesthe entrance 4D of the washing tub 4 from the upper side Z1.

The pump 12 is a centrifugal pump equipped with a rotating impeller (notshown) or the like, and is provided in the circulation path 11. Whenbeing driven, the pump 12 pumps the detergent solution in the outer tub3 and the washing tub 4 into the end 11A of the circulation path 11 viathe drainage path 9, so as to raise the detergent solution in thecirculation path 11. As a result, the detergent solution is pumped intothe circulation path 11 from the outer tub 3 and the washing tub 4, andis discharged from the water discharge opening 11B at the end 11C. Thedetergent solution discharged from the discharge opening 11B flows downto the entrance 4D of the washing tub 4 as indicated by a thick brokenline arrow, and is returned to the washing tub 4 from the upper side Z1.When the pump 12 is continuously driven, the detergent solutioncirculates between the washing tub 4 and the circulation path 11.

The washing machine 1 includes a controller 30 as an execution unit. Thecontroller 30 is, for example, a microcomputer including a centralprocessing unit (CPU) and a memory such as a read only memory (ROM) anda random access memory (RAM), and is disposed in the housing 2.

Referring to FIG. 2, i.e. a block diagram illustrating an electricalstructure of the washing machine 1, the washing machine 1 furtherincludes a water level sensor 31, a rotation sensor 32, and a timer 33for measuring time. Each of the water level sensor 31, the rotationsensor 32 and the timer 33 and the motor 5, the pump 12, the displayoperation portion 15, the water supply valve 7 and the drain valve 10described above is electrically connected to the controller 30.

The water level sensor 31 is a sensor for detecting the water level ofthe outer tub 3 and the washing tub 4, and a detection result of thewater level sensor 31 is input to the controller 30 in real time.

The rotation sensor 32 is a device for reading the number of revolutionsof the motor 5, strictly speaking, the number of revolutions of theoutput shaft 18 of the motor 5. For example, the rotation sensor 32 isformed by a Hall IC (not shown) that outputs a pulse each time theoutput shaft 18 rotates by a predetermined rotation angle. The number ofrevolutions read by the rotation sensor 32 is input to the controller 30in real time. The controller 30 controls a voltage applied to the motor5 based on the input number of revolutions. More specifically, thecontroller 30 controls the duty ratio of the voltage applied to themotor 5 to drive the motor 5 to rotate at the desired number ofrevolutions. The controller 30 also controls the driving of the pump 12.

As described above, in response to selecting operation conditions of thewashing operation by the user through the display operation portion 15,the controller 30 accepts the selection. The controller 30 performscontrol to display information necessary to the user in the displayoperation portion 15 in a visible manner. The controller 30 controlsopening/closing of the water supply valve 7 and the drain valve 10.Therefore, the controller 30 can supply water to the washing tub 4 byopening the water supply valve 7 with the drain valve 10 being closed,and can drain the washing tub 4 by opening the drain valve 10.

Next, the washing operation executed by the controller 30 in the washingmachine 1 will be described. The washing operation includes a washingprocess consisting of an original circulation-soaking process and anormal washing process after the circulation-soaking process, a rinsingprocess after the washing process, and a dewatering process. Thecirculation-soaking process may be regarded as an independent process inthe washing operation or may be regarded as part of the washing processas in the present embodiment. The dewatering process includes a finaldewatering process executed at the end of the washing operation and anintermediate dewatering process executed after the washing process andthe rinsing process.

The controller 30 detects the amount of washings Q in the washing tub 4as a load amount before starting the washing operation. The unit of theload amount is, for example, kg. As an example of detecting the loadamount, the controller 30 may acquire the load amount from the weight ofthe washings Q detected by a weight sensor (not shown) provided in thewashing machine 1. Further, the load amount may be detected byvariations in the number of revolutions of the motor 5 when the washingtub 4 is steadily rotated at a low speed. In the case that the pulsatordescribed above is provided, the controller 30 stops the driving of themotor 5 immediately after rotating the pulsator carried with thewashings Q for a predetermined time, thereby rotating the motor 5inertly, and the inertial rotation amount of the motor 5 at that time ismeasured. The larger the load amount is, the smaller the inertialrotation amount of the motor 5 connected to the pulsator carried withthe heavy washings Q will be. The smaller the load amount is, the largerthe inertia rotation amount of the motor 5 connected to the pulsatorcarried with the light washings Q will be. The controller 30 detects theload amount according to the magnitude of the inertia revolutions.

The circulation-soaking process will be described with reference to theflowchart of FIG. 3. During the circulation-soaking process, the drainvalve 10 is always in a closed state. As the circulation-soaking processstarts, the controller 30 controls the water supply valve 7 to open fora predetermined time to supply water to the washing tub 4 (step S1). Asa result, the detergent solution is accumulated in the washing tub 4 toa predetermined water level.

Next, the controller 30 performs the circulation process for the firsttime (step S2). In the circulation process, the controller 30 controlsthe pump 12 to circulate the detergent solution between the washing tub4 and the circulation path 11, and the detergent solution is sprayed tothe washings Q in the washing tub 4 from the discharge opening 11B ofthe circulation path 11 during the circulation process. The time forperforming the circulation process, that is, the time for driving thepump 12 is, for example, about 15 seconds. Moreover, the detergentsolution which has passed through the pump 12 in the circulation path 11is finely crushed by the impeller of the pump 12 and dissolved in water,so that the detergent solution of high concentration is generated.

Next, the controller 30 performs the soaking process for the first time(step S3). In the soaking process, the controller 30 performs control tostop the driving of the pump 12 to soak the washings Q in the detergentsolution in the washing tub 4. Specifically, the detergent solutionsprayed from the upper side Z1 to the washings Q in the circulationprocess soaks into the washings Q due to its own weight. In addition, inthe soaking process, since the drain valve 10 is continuously closed,the detergent solution is accumulated in the washing tub 4 so that thewashings Q, particularly the lower part of the washings Q, is immersedin the detergent solution. The time for performing the soaking process,that is, the time during which the pump 12 is stopped is, for example,about 45 seconds.

Next, the controller 30 performs the circulation process for the secondtime (step S4), and then performs the soaking process for the secondtime (step S5). In addition, since the pump 12 is stopped in the soakingprocess just before the circulation process, at the start of thecirculation process, the detergent solution is in a state of beingaccumulated in the outer tub 3 and the washing tub 4 and accumulated atthe end 11A of the drainage path 9 and the circulation path. Therefore,during the circulation process immediately after the soaking process,the pump 12 can promptly start the circulation of detergent solutionwithout idling. Further, in the first circulation process, since thewashings Q before washing are dry and can absorb a large amount ofdetergent solution, the time for the first circulation process is set tobe longer. However, the washings Q are in a state of having absorbed acertain amount of detergent solution since the start of the secondcirculation process, the time for the circulation process is set to beshorter than that of the first circulation process. Based on the samereason, the time for the first soaking process is set to be longer inthe first soaking process, while the time for subsequent soakingprocesses since the second soaking process is set to be shorter thanthat of the first soaking process.

The controller 30 alternately repeats the circulation process (step S4)and the soaking process (step S5) for a plurality of times until apredetermined time has elapsed from supplying water in step S1 (No instep S6). The predetermined time herein is, for example, 30 minutes. Inthis case, the circulation process and the soaking process are repeated30 times in total. Even if there is little detergent solution, thedetergent solution is uniformly applied to the washings Q in the washingtub 4 repeatedly through a plurality of circulation processes, and thewashings Q are brought to a state equivalent to being soaked in thedetergent solution through the soaking processes after the circulationprocesses. As a result, the dirt is effectively dissolved out thewashings Q. Therefore, the cleaning effect can be improved with littledetergent solution.

When the predetermined time has elapsed (Yes in step S6), thecirculation-soaking process is completed, and the controller 30 performsthe next process, i.e., the normal washing process. When the normalwashing process is started, the controller 30 controls the water supplyvalve 7 to open with the drain valve 10 being continuously closed, so asto supply water to the washing tub 4 additionally. As a result, thedetergent solution is accumulated in the washing tub 4 to a water levelhigher than the water level of the detergent solution accumulated due tothe supplied water in step S1. In the normal washing process, thecontroller 30 drives the motor 5 under a state that the detergentsolution is stored in the washing tub 4, so as to rotate the washing tub4 or the pulsator described above. As a result, a water flow of thedetergent solution is generated in the washing tub 4 to stir thewashings Q. The dirt is removed from the washings Q by the mechanicalforce such as friction and vibration given to the washings Q by thewater flow, or the dirt is chemically decomposed by the detergentsolution, whereby the washings Q are washed formally. In particular, dueto the circulation-soaking process before the normal washing process,the washings Q are in a state that the dirt is dissolved out to beeasily removed, thus a high cleaning effect can be exhibited in thenormal washing process.

The controller 30 may further execute a first process, in which themotor 5 is driven to rotate the washing tub 4 at a low speed below apredetermined rotation speed, in at least one circulation process. Thenumber of revolutions of the motor 5 when the washing tub 4 is rotatedat a low speed is, for example, 50 rpm. In addition, the number ofrevolutions of the motor 5 when the washing tub 4 is rotated at a highspeed in the dewatering process is, for example, 600 rpm to 800 rpm. Byrotating the washing tub 4 at a low speed in the circulation process, itis possible to suppress the bias of the washings Q in the washing tub 4,and prevent the detergent solution in the washing tub 4 from beingscattered to the outside from the entrance 4D. Further, the controller30 may further execute a second process, in which the motor 5 is drivento perform an intermittent rotation of the washing tub 4 repeatedly, inat least one circulation process. The intermittent rotation of thewashing tub 4 refers to stopping or rotating the washing tub 4repeatedly by turning on or turning off the motor 5 repeatedly.

Through the first process and the second process, the detergent solutionreturned to the washing tub 4 from the circulation path 11 is sprayed tothe washings Q in the washing tub 4 over the entire region in therotation direction of the washing tub 4. Therefore, it is possible tofurther improve the cleaning effect by detergent solution.

The controller 30 can also perform a third process, in which the washingtub 4 is stopped during the circulation process and the motor 5 isdriven to rotate the washing tub 4 for only a predetermined angle beforestarting the next circulation process, in the circulation-soakingprocess. In this way, when the washing tub 4 is stopped during thecirculation process, it is possible to intensively spray the washingwater on a part of the washings Q in the rotational direction thewashing tub 4 containing. Then, the washing tub 4 slightly rotatesbefore starting the next circulation process, so that in the nextcirculation process, the washing water is intensively sprayed on a partof the washings Q other than the part sprayed by the washing water inthe previous circulation process. By repeating the circulation process aplurality of times while slightly changing the position of the washingsQ immersed in the detergent solution, a sufficient amount of detergentsolution is uniformly sprayed to the washings Q in the washing tub 4over the entire region in the rotation direction of the washing tub 4finally. Therefore, the cleaning effect caused by the detergent solutionis further improved. It should be noted that, in the case of the thirdprocess, the washing tub 4 may stop or rotate in a soaking processimmediately after the circulation process in which the washing tub 4stopped. In the case that the washing tub 4 rotates in the soakingprocess, the controller 30 temporarily stores the stop position of thewashing tub 4 in the previous circulation process.

In the circulation-soaking process, only one of the first process, thesecond process and the third process may be performed, or a combinationof the first process, the second process and the third process may becarried out. For example, in the first to fifth circulation process inthe early stage of the circulation-soaking process, only the firstprocess is performed, and in the sixth circulation process andsubsequent circulation processes, only the third process is performed.In this case, it is possible to uniformly spray the detergent solutionthroughout the whole washings Q at an early stage in thecirculation-soaking process through the first to fifth circulationprocess, and in subsequent circulation process since the sixthcirculation process, a large amount of detergent solution is locallysprayed to the washings Q, so that it is possible to improve thecleaning effect of the part of the washings Q immersed in the detergentsolution.

Further, a combination of the first to third processes can bearbitrarily set according to the load amount of the washings Q and thewashing operation mode. For example, in the case that the load amount issmall due to a small amount of washings Q or under a mode in whichcotton easy to absorb water is washed, the detergent solution is easilyimmersed into the lower part of the washings Q even if little detergentsolution is uniformly sprayed to the washings Q. Therefore, thefrequencies of the first and second processes are increased, and thefrequency of the third process is reduced. On the other hand, in thecase that the load amount is large due to the large number of washings Qor under a mode in which thick blankets are washed, if no large amountof detergent solution is intensively sprayed on a part of the washingsQ, the detergent solution can hardly immerse into the lower part of thewashings Q. Therefore, the frequency of the third process is increased,and the frequencies of the first and second processes are reduced.

The controller 30 may open the water supply valve 7 in step S1 of thecirculation-soaking process, so as to supply a part of water suppliedduring the entire washing process to the washing tub 4 to generate thedetergent solution. That is, the detergent solution is generated in thecirculation-soaking process by using a part of the water supply amountpredetermined in the entire washing process. As a result, it is possibleto generate the detergent solution of high concentration withoutincreasing the amount of water supplied during the entire washingoperation. In addition, the water supply amount in the whole washingprocess is, for example, 60 L. In this case, the water supply amount inthe circulation-soaking process is set to be about ½ to ½ of 60 L, forexample, 20 L.

In this manner, in the circulation process, by generatinghigh-concentration detergent solution with little detergent and waterand repeating the circulation-soaking process in which the detergentsolution is uniformly immersed into the washings Q via the pump 12, itis possible to obtain the same cleaning effect as that obtained in thecase of washing by using a large amount of detergent solution of highconcentration. In addition, the high concentration herein is, forexample, a range of 2 to 3 times the concentration.

In addition, as described above, when water is supplied in step S1,water containing the detergent, which has passed through the detergentcontainer 8, is discharged from the discharge opening 6B of the watersupply path 6 to the position away from the washings Q in the washingtub 4. That is, during the supplying water in the circulation-soakingprocess, the water containing the detergent from the detergent container8 is supplied without being sprayed on the washings Q directly. As aresult, it is possible to prevent the following situation: the detergenthaving an excessively high concentration only adheres to a part of thesurface of the washings Q before being dissolved into the water, so thatit is difficult to clean the entire washings uniformly.

The controller 30 may also change the time of the circulation processand the time of the socking process according to the load amount of thewashings Q in the washing tub 4 respectively. Specifically, when theload is large due to large number of washings Q, it is necessary tospray a large amount of detergent solution on the washings Q to immersethe washings, thus the time of the circulation process and the time ofthe soaking process are generally set by the controller 30 to be long.On the other hand, when the load is little due to a small amount ofwashings Q, a sufficient washing effect can be obtained by sprayinglittle detergent solution to immerse the washings Q, thus the time ofthe circulation process and the time of the soaking process aregenerally set by the controller 30 to be short. As a result, it ispossible to execute a most suitable circulation-soaking process on thebasis of the load amount. Therefore, the cleaning effect brought by thedetergent solution in the circulation-soaking process can be furtherimproved.

The present disclosure is not limited to the embodiments describedabove, and various modifications are possible within the scope of theclaims.

For example, in the embodiment described above, the end 11A of thecirculation path 11 is connected to the drainage path 9 (see FIG. 1),but it may be connected to the lower end of the outer tub 3.

FIG. 4 is a schematic view illustrating a washing machine 1 according toa first modification. FIG. 5 is a schematic diagram illustrating awashing machine 1 according to a second modification. FIG. 6 is aschematic diagram illustrating a washing machine 1 according to a thirdmodification. In FIGS. 4 to 6, the same parts as those described withreference to FIG. 1 are denoted by the same reference numerals, and adescription thereof will be omitted. As shown in the first to thirdmodifications of FIGS. 4 to 6, the washing machine 1 may further includea tank 21.

Referring to FIG. 4, the tank 21 has a capacity capable of storing thedetergent solution generated in the circulation washing process, and isdisposed in the housing 2 in a space that is closer to the lower side Z2than the outer tub 3 is. The tank 21 is interposed in the drainage path9, and is located between a connecting portion between the end 11A ofthe circulation path 11 and the drainage path 9 and the end 9A of thedrainage path 9. The internal space of the tank 21 constitutes anintermediate portion of the drainage path 9. A drain valve 22 isprovided between the end 9A and the tank 21 in the drainage path 9.Hereinafter, for convenience of description, the drain valve 10 isreferred to as a first drain valve 10, and the drain valve 22 isreferred to as a second drain valve 22. The opening and closing of thesecond drain valve 22 is controlled by the controller 30.

When both the first drain valve 10 and the second drain valve 22 areopened, the water flowing to the drainage path 9 from the outer tub 3 isdischarged outside the machine once it passes through the tank 21 andreaches the other end 9B. On the other hand, when the first drain valve10 is closed with the second drain valve 22 being opened, the waterflowing to the drainage path 9 from the outer tub 3 is stored in thetank 21 rather than being discharged outside the machine. The tank 21 isconnected to an end 23A of an air vent pipe 23 from the upper side Z1.The air vent pipe 23 extends from the end 23A to the upper side Z1, andanother end 23B of the air vent pipe 23 is connected to the upperportion of the circumferential wall 3A of the outer tub 3. As a result,the air in the tank 21 escapes into the outer tub 3 through the air ventpipe 23, so that the water flowing to the drainage path 9 from the outertub 3 can flow smoothly into the tank 21. Moreover, even if bubbles inthe tank 21 enter the air vent pipe 23, the bubbles are guided into theouter tub 3, thus it is possible to prevent the bubbles from blockingthe air vent pipe 23.

In the first to third modifications, the controller 30 executes thecirculation-soaking process illustrated in FIG. 3. In thecirculation-soaking process, the first drain valve 10 is always in aclosed state, and the second drain valve 22 may be opened and closed asnecessary. In addition, when the second drain valve 22 is always opened,since the tank 21 functions only as a part of the drainage path 9, acirculation-soaking process, which is the same as that performed in thecase that the tank 21 is not provided, is executed.

On the other hand, in the circulation-soaking process in which thesecond drain valve 22 is opened or closed as needed, the detergentsolution is accumulated in the tank 21 because the controller 30performs control to supply water with the second drain valve 22 beingopened in Step S1. Then, the controller 30 alternately repeats thecirculation process and the soaking process until the predetermined timeelapsed in step S6.

In the circulation process in step S2 or step S4, after the detergentsolution stored in the tank 21 is pumped into the circulation path 11 bythe pump 12, the detergent solution is sprayed to the washings Q in thewashing tub 4 from the upper side Z1 by means of the discharge opening11B of the circulation path 11 (see the thick dashed arrow in FIG. 4).The detergent solution sprayed to the washings Q is accumulated in thetank 21 through the drainage path 9, pumped into the circulation path 11again by the pump 12, and is sprayed to the washings Q. As a result, inthe circulation process, the detergent solution circulates between thewashing tub 4 and the circulation path 11 via the tank 21. It should benoted that, in the first circulation process in step S2, in order toimmerse a large amount of detergent solution into the washings Q in adry state before washing, the second drain valve 22 may be closed sothat the detergent solution is stored in the washing tub 4.

On the other hand, in the soaking process in step S3 or step S5, thecontroller 30 first closes the second drain valve 22 while stopping thepump 12. As a result, the detergent solution supplied to the washing tub4 from the circulation path 11 in the previous circulation process isaccumulated in the washing tub 4, thus the detergent solution can easilyimmerse into the washings Q. Moreover, the controller 30 opens thesecond drain valve 22 at a timing in the final stage when apredetermined time has elapsed from the start of the soaking process. Asa result, the detergent solution in the washing tub 4 is accumulated inthe tank 21 through the drainage path 9, so that circulation of thedetergent solution can be promptly started in the circulation processthat is immediately performed.

When the predetermined time has elapsed (Yes in step S6) and the normalwashing process is performed, the controller 30 closes the second drainvalve 22 and opens the water supply valve 7 to supply water to thewashing tub 4 along with the start of the normal washing process. Inthis case, the pump 12 is driven to transfer the detergent solution inthe tank 21 to the washing tub 4 via the circulation path 11. In thisway, by utilizing the detergent solution of the tank 21 for supplyingwater, water supplied from the water supply path 6 can be suppressed tobe little.

As described above, in step S1 of supplying water in thecirculation-soaking process, as a structure for supplying watercontaining the detergent without spraying the detergent solution on thewashings Q directly, the discharge opening 6B of the water supply path 6is provided as follows: as indicated by the arrow in thick solid line,the water containing the detergent is discharged toward the gap 19between the outer tub 3 and the washing tub 4, that is, toward theposition away from the washings Q in the washing tub 4. As amodification of this structure, a second modification and a thirdmodification can be exemplified.

In the second modification shown in FIG. 5, the water supply path 6passes through the detergent container 8, and extends to the lower sideZ2 between the circumferential wall 3A of the outer tub 3 and thehousing 2. Another end 6C of the water supply path 6 is connected to thelower end of the circumferential wall 3A. In this case, the water supplypath 6 is a flow path outside the outer tub 3, and the discharge opening6B at the end 6C faces the lower end of the gap 19 between the outer tub3 and the washing tub 4 in the lateral direction Y. On the other hand,the washing machine 1 of the second modification includes a branch path25 branched from the water supply path 6 in the detergent container 8.The branch path 25 is a flow path extending from the detergent container8 to the lower side Z2. At the lower end of the branch path 25, a watersupply port 25A facing the entrance 4D of the washing tub 4 from theupper side Z1 is provided. A water supply valve 26 is provided in thebranch path 25. In the following description of the second modification,the water supply valve 7 is referred to as a first water supply valve 7,and the water supply valve 26 is referred to as a second water supplyvalve 26 for convenience. The opening and closing of the second watersupply valve 26 are controlled by the controller 30.

In the circulation-soaking process in the second modification, whenwater is supplied in step S1, the controller 30 opens the first watersupply valve 7 and closes the second water supply valve 26. As a result,the water from the faucet passes through the detergent container 8 tocarry the detergent, flows down to reach the supply path 6, and then issupplied to a space 27 inside the outer tub 3 from the discharge opening6B, as indicated by a thick solid arrow. The space 27 is closer to thelower side Z2 than the bottom wall 4B of the washing tub 3. At thistime, the discharge opening 6B discharges the water flowing through thewater supply path 6 toward the space 27, that is, the position away fromthe washings Q in the washing tub 4. As a result, the water containingthe detergent is supplied without being sprayed on the washings Qdirectly. On the other hand, in the case of supplying water in thenormal washing process performed after the circulation-soaking process,the controller 30 closes the first water supply valve 7 and opens thesecond water supply valve 26. As a result, the water from the faucet isdirectly supplied into the washing tub 4 from the water supply port 25Athrough the branch path 25. That is, the water supply path 6 is used tosupply water initially, and the branch path 25 is used to supply waterthereafter.

In the third modification shown in FIG. 6, the end 6C of the watersupply path 6 passes through the entrance 3D of the outer tub 3, and thedischarge opening 6B at the end 6C faces the entrance 4D of the washingtub 4 from the upper side Z1. In the washing machine 1 of the thirdmodification, a guiding portion 28 is provided inside the washing tub 4.The guiding portion 28 is a groove extending in the up-down direction Zalong the axis J over a range from the upper end to the lower end of thecircumferential wall 4A of the washing tub 4, and the plan cross sectionthereof is configured in an arc shape curved toward the axis J side. Theguiding portion 28 is fixed to the circumferential wall 4A so as tocover one circumferential portion of the circumferential wall 4A fromthe axis J side. As a result, a guide flow path 29 extending in theup-down direction Z is formed between the guiding portion 28 and thecircumferential wall 4A. The upper end of the guiding portion 28 is areception portion 28A formed in a bowl shape bulging toward the axis J.The guide flow path 29 is exposed from the reception portion 28A to theupper side Z1. The discharge opening 6B is opposed to the receptionportion 28 A from the upper side Z1.

In the circulation-soaking process in the third modification, thecontroller 30 opens the water supply valve 7 when water is supplied instep S1. As a result, the water from the faucet passes through thedetergent container 8 to carry the detergent, passes through the watersupply path 6, and falls from the discharge opening 6B to the receptionportion 28A of the guiding portion 28 as indicated by a thick solidarrow. The water received by the reception portion 28A flows down theguide path 29, is leaked from the through holes 4E of the washing tub 4to the outside of the washing tub 4, and reaches the space 27 inside theouter tub 3 that is closer to the lower side Z2 than the bottom wall 4Bof the washing tub 4. At this time, the discharge opening 6B dischargesthe water flowing through the water supply path 6 toward the guidingportion 28, that is, the position away from the washings Q in thewashing tub 4. As a result, the water containing the detergent issupplied without being sprayed on the washings Q directly.

What is claimed is:
 1. A washing machine, comprising: a washing tub having an axis extending longitudinally, wherein the washing tub is configured to accommodate washings and is capable of storing water; a circulation path configured to draw detergent solution mixed with a detergent in the washing tub and return the detergent solution into the washing tub from an upper side; a pump configured to pump the detergent solution in the washing tub into the circulation path and allow the detergent solution to rise in the circulation path; and an execution unit configured to execute a washing operation, wherein the washing operation comprises a circulation-soaking process during which a circulation process and a soaking process are conducted alternately and repeatedly, wherein the detergent solution is circulated between the washing tub and the circulation path by driving the pump and sprayed onto washings in the circulation process, and the pump is stopped from being driven and the washings are soaked with the detergent solution in the washing tub in the soaking process.
 2. The washing machine according to claim 1, further comprising a motor for rotating the washing tub, wherein the execution unit is configured to drive the motor to rotate the washing tub at a low speed below a predetermined rotation speed in at least one circulation process.
 3. The washing machine according to claim 1, further comprising a motor for rotating the washing tub, wherein the execution unit is configured to drive the motor to rotate the washing tub repeatedly an intermittently in at least one circulation process.
 4. The washing machine according to claim 1, further comprising a motor for rotating the washing tub, during the circulation-soaking process, the execution unit is configured to cause the washing tub to stop in the circulation process, and drive the motor to rotate the washing tub merely for a predetermined angle prior to starting a next circulation process.
 5. The washing machine according to claim 1, further comprising: a water supply path configured to supply water to the washing tub, and a water supply valve configured to open and close the water supply path, wherein the washing operation comprises a washing process consisting of the circulation-soaking process and a normal washing process, in the normal washing process, water is accumulated in the washing tub to perform a normal washing of the washings after the circulation-soaking process, wherein during the circulation-soaking process, the execution unit is configured to open the water supply valve, so as to supply a part of a total water supply amount in the whole washing process to the washing tub and generate the detergent solution.
 6. The washing machine according to claim 5, further comprising a detergent container connected to the water supply path and containing the detergent, wherein the water supply path is provided with a discharge opening, and water flowing through the water supply path after passing through the detergent container is discharged from the discharge opening toward a position away from the washings in the washing tub.
 7. The washing machine according to claim 1, wherein the execution unit is configured to change a time for performing the circulation process and a time for performing the soaking process according to load amount of the washings inside the washing tub.
 8. The washing machine according to claim 2, further comprising: a water supply path configured to supply water to the washing tub, and a water supply valve configured to open and close the water supply path, wherein the washing operation comprises a washing process consisting of the circulation-soaking process and a normal washing process, in the normal washing process, water is accumulated in the washing tub to perform a normal washing of the washings after the circulation-soaking process, wherein during the circulation-soaking process, the execution unit is configured to open the water supply valve, so as to supply a part of a total water supply amount in the whole washing process to the washing tub and generate the detergent solution.
 9. The washing machine according to claim 3, further comprising: a water supply path configured to supply water to the washing tub, and a water supply valve configured to open and close the water supply path, wherein the washing operation comprises a washing process consisting of the circulation-soaking process and a normal washing process, in the normal washing process, water is accumulated in the washing tub to perform a normal washing of the washings after the circulation-soaking process, wherein during the circulation-soaking process, the execution unit is configured to open the water supply valve, so as to supply a part of a total water supply amount in the whole washing process to the washing tub and generate the detergent solution.
 10. The washing machine according to claim 4, further comprising: a water supply path configured to supply water to the washing tub, and a water supply valve configured to open and close the water supply path, wherein the washing operation comprises a washing process consisting of the circulation-soaking process and a normal washing process, in the normal washing process, water is accumulated in the washing tub to perform a normal washing of the washings after the circulation-soaking process, wherein during the circulation-soaking process, the execution unit is configured to open the water supply valve, so as to supply a part of a total water supply amount in the whole washing process to the washing tub and generate the detergent solution.
 11. The washing machine according to claim 2, wherein the execution unit is configured to change a time for performing the circulation process and a time for performing the soaking process according to load amount of the washings inside the washing tub.
 12. The washing machine according to claim 3, wherein the execution unit is configured to change a time for performing the circulation process and a time for performing the soaking process according to load amount of the washings inside the washing tub.
 13. The washing machine according to claim 4, wherein the execution unit is configured to change a time for performing the circulation process and a time for performing the soaking process according to load amount of the washings inside the washing tub.
 14. The washing machine according to claim 5, wherein the execution unit is configured to change a time for performing the circulation process and a time for performing the soaking process according to load amount of the washings inside the washing tub.
 15. The washing machine according to claim 6, wherein the execution unit is configured to change a time for performing the circulation process and a time for performing the soaking process according to load amount of the washings inside the washing tub. 